Improved slide-valve for steam-engines



UNITED STATES PATENT OEETCE.

ALEXANDER BUCHANAN, OF NEW' YORK, N. Y.

IIVIPROVED SLIDE-VALVE FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 36,94 l. dated November18, 1862.

To all whom, it may concern:

Be it known that I, ALEXANDER BUCHANAN, of the city, county, and Stateof New York, have invented a new and useful Improvement in Valves forthe Induction and Eduction of Steam to and from the Cylinders ofSteam-Engines; and I do hereby declare that the following is a full,clear, and exact description of the same, reference being had to theaccompanying drawings, forming part of this speciiication, in which-Figure l is a plan view of the interior of the steamchest of an enginehaving my invention applied. Fig. 2 is a central longitudinal verticalsection of the steam chest and valve and their appurtenances. Fig. 3 isa transverse vertical section of the same.

Similar letters of reference indicate corresponding parts in all thefigures.

This invention relates to that kind of valve which may be termed theoscillating segment7 valve-that is to say, which is constructed with itsface in the form of a portion of the periphery of cylinder, and isarranged to oscillate about a fixed axis in a seat of correspondingform.

The improvement consists, principally, in combining the valve with thependulum or oscillating arm, to which it is attached by meansof aiiexible and elastic plate, which constitutes a portion of the back or"the valve, and which, while it allows the greater portion of thepressure produced by the steam on the back of the valve to betransmitted to a iixed bearing at the axis of oscillation, at the sametime permits the valve to be pressed against the seat with suflicientforce to counteract the tendency to lift the valve, which is produced bythe pressure of the steam in the ports during portions of the stroke ofthe valve.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

c c is the concave arc-formed valve-seat, having the ports b b c,arranged, as is customary, in the seat ofthe common slide-valve. A, B,C, and D represent the different portions of the valve. The portion A,composed of a single frame-like casting, constitutes the face, ends, andsides of the valve, and contains the exhaust-chamber h, but is madewithout a top or back, that being formed by the plates B and C. Theplate B is made of wrought or cast iron stout enough to insure itsperfect rigidity under all the circumstances of the operation, and is ofa form corresponding with the upper or back portion of the chamber L,but sufficiently smaller to have a narrow opening between them, as shownat j j in Fig. l, all round the plate. I prefer the form of the saidplate and of the back part of the chamber h, in which it is received, tobe of oblong form with the ends rounded, as shown in Fig. l, where partof the said plate is exposed to view by breaking away a portion of theplate C above it, and the remainder is shown in dotted outline. The topor cap plate C, made of thin copper, brass, steel, or other flexible andmoderately elastic metal, covers the whole of the top of the portion A,and is secured thereto in such manner as to be perfectly steam-tight bythe gland D, which is screwed down upon it by screws t t', screwing intoA. The rigid plate B, which may be termed the sustaining77 plate, isrmly secured to the thin plate C by riveting or otherwise, to prevent itfrom bending or springing in anypart which covers the chamber h, exceptin the part which covers the space j j, between the plate B and frame A,and this part is swaged or otherwise formed with a deep groove on theunder side and a corresponding projection on the other side, as shown atk lr, to give it a certain degree of flexibility.

E is a rock-shaft, from which the valve is suspended by the pendulum orvibrating arm I, supported in bearings Z Z in fixed standards F F,supported by a bridge, G, placed across the interior of the valve-chestH. The distance between the axis of the rock-shaft E and the valve-seatis equal to the exact radius of the arc of the faces of the valve andseat. In order to enable the said rock-shaft to be adjusted to bring itsaxis exactly concentric with the arc of the valveseat, the bearings Z Zshould have suitable packing or adjusting plates or pieces applied belowthem and at their sides. The plates B C of the valve are secured to thelower part of the pendulum or vibrating arm I by means of a gimbal oruniversal joint p q r, to enable the valve to accommodate itself to theseat in case of any eccentricity occurring between the rock-shaft andthe seat. The said pendulum or arm passes through a slot, and therock-shaft is secured therein by wedges m m, above and below therockshaft, which enables it to be adjusted to the proper effectivelength. The valve-chest cover H has an opening provided in it for thestandards F F, and this opening is covered by a cap, H2, which is deepenough to admit the yvalve-chest, the connection of the stem and yokebeing sueh that the yoke can oscillate -to accommodate itself to thecurved movement of the valve.

1 To adj ust the valve for operation, the bearings of the rock-shaft arebrought to a position to make its axis concentric with the valveseat,and the pendulum or arm I is so adjusted that the face of the valve maywork just in contact with the seat; but the pendulum -may be afterwardraised by the wedges m on, or their equivalents, in such manner as toraise the valve slightly from the seat.

Vhen the cover has been applied and secured to the steam-chest, andsteam is admit ted thereinto, the pressure of the steam, acting on thewhole of the back of the valve, tends to depress the portion A and bringthe face in contact with the seat, such depression being permitted bythe ilexure of the grooved portion of the plate C; but the elasticity ofthe said plate prevents any more of such press` ure being transmittedthrough the face to the seat than is necessary to overcome thebackpressure to which those portions of the face .which cover the portsb b are subject while the induction is taking place through them, orafter the steam has been cut off from them and before they are broughtinto communication with the exhaust-chamber h, the remainder of thepressure being transmitted to the bearings Z Z by the sustaining-plateB, pendulum or arm I, and rock-shaft E. The pressure allowed to betransmitted by the valve to the seat is regulated by the setting up' ofthe pendulum or arm more or less by the Wedges m m or their equivalents.

In order to permit the valve to rise instantly from its seat, as isdesirable in case of the sudden reversal of the action of the steam onthe piston in a loeomotiveengine, the bearings provided in the ports r rof the universal joint, that are attached directly and rigidly to theplates B C for the reception of the pivots ofthe ring q (l of the saidjoint, should be left open at the bottom or elongated in a downwarddirection, or the bearings Z Z should be left open at the top orelongated in an upward direction; or both of these expedients may beresorted to.

This invention may be adapted to an old engine without providing a newsteam-chest by securing to the old flat Valve-seat a plate in which theconcave or arc-formed seat ce ce is formed, the parts in the seat a abeing made to correspond in position with those of the old one. Figs. 2and 3 illustrate such an adaptation.

In the figures the line e e represents the old seat, and L indicates theplate on which the cone-ave seat a a is formed.

/Vhat I claim as my invention, and desire to secure by Letters Patent,s-

Combining an oscillating segment-valve, A, with the pendulum orOscillating arm I, which suspends it from fixed bearings by means of aflexible and elastic plate, C, or its equivalent, constituting a portionofthe back ofthe Valve, substantially as and for the purpose hereinspecified.

ALEXR. BUCHANAN.

Vitnesses:

J AMEs LAIRD, RICHARDSON GAwLnY.

